Magnetic impulse switch



March 22, 1960 J. B. CAMP 2,929,945

MAGNETIC IMPULSE SWITCH Filed April 6, 1956 Amplifier R. JAMES B. CAMP,

his Af/omey.

MAGNETIC IMPULSE SWITCH James B. Camp, Fairlield, Ala., assignor to United States Steel Corporation, a corporation of New Jersey Application April 6, 1956, Serial No. 576,601 Claims. (Cl. 310-156) This invention relates to a magnetic impulse switch and more particularly to such a switch for use with a' shear drum used in a continuous strip processing line. In such lines the strip is inspected for defects such as pin holes and then isautomatically cut into sheets of the desired length by means of a rotating shear after which the sheets are directed into separate piles depending upon whether they are prime or defects. The specific sheet containing a defect must be identified in order to direct it into the proper pile. In my copending application Serial No. 258,700, filed November 28, 1951, I have shown a classifier control for this purpose. The control must know the position of the defect in respect to the instance of cutting by the rotating shear. In my copending application I utilize a mechanical switch 26 for this purpose. The switch disclosed therein requires frequent adjustment to compensate for mechanical wear.

It is an object of my invention to provide a switch which has no wearing parts and is accurate in operation.

This and other objects will be more apparent after referring to the following specification and attached drawings, in which:

Figure 1 is an elevation of the switch of my invention with parts broken away; and

Figure 2 is a view taken on the line IIII of Figure 1 and showing the switch of my invention as connected to a shear drum.

Referring more particularly to the drawings, the reference numeral 2 indicates a shear drum having a cutter 4 thereon. The shear drum 2 is mounted on a shaft 6 which is supported in the usual manner by machine frame 8. The shaft passes through an oil seal 10 which is supported in a bracket 12 carried by machine frame 8. A non-magnetic ring 14 is mounted on the shaft 6 by means of set screws 16 passing through threaded holes 18 in the ring 14. The ring 14 has a radial opening 20 therethrough for receiving a permanent magnet 22 which has a wedge shaped outer portion with its apex 24 arranged transversely of the ring. A magnetic pick-up head 26 is mounted adjacent the periphery of the ring 14 and is supported by the bracket 12 in any suitable manner. The

magnetic pick-up consists of a core 28 having a wedge shaped inner end and a coil 32 surrounding the core. Leads 34 and 36 are preferably connected to an amplifier 38. A shield 4!].surrounds the pick-up head 26 and has an opening 42 therein on the side facing the ring 14. The opening 42 preferably flares outwardly away from the ring as shown.

The operation of my device is as follo'ws:

When the shear is in operation the magnet 22 passes the pick-up head 26 and induces a pulse voltage between its output terminals 34 and 36. The position of the ring 14 is adjusted so that this pulse of voltage occurs at the same time that the shear is cutting the strip. After this position has been determined the ring 14 is permanently anchored to the shaft 6 and no further adjustment is necessary. The voltage pulse is normally amplified by the amplifier 38 and fed into the classifier control of nited States Patent 6 fit my above mentioned patent. The shield 40 directs the lines of flux around the core 28 until the magnet 22 is almost directly under the core. The wedge shape of the magnet tends to concentrate the lines of flux. The reduced cross sectional area of the shield 40 as it approaches the core 28 increases the reluctance between the shield and the core, thereby reducing the tendency of the magnetic lines of force to stray into the shield 40 when the magnet is directly under the core. The ring 14 need not be directly connected to the shear shaft but should be connected so that it rotates synchronously with the shear drum.

While one embodiment of my invention has been shown and described it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. In combination with a rotatable shear drum, a magnetic impulse generator comprising a rotatable non-magnetic member, a single magnet mounted on said member adjacent the periphery thereof, a stationary magnetic pick-up head mounted adjacent the periphery of said member, means for rotating said member in synchronism with said shear drum so that said magnet passes said pick-up head at the same time as the shear is cutting, and a magnetic shield surrounding said pick-up head, said shield having an opening therein on the side facing the member, said opening being in a plane through the axis of said pick-up head and the axis of rotation of said member.

2. In combination with a rotatable shear drum, a magnetic impulse generator comprising a rotatable non-magnetic member, a single magnet mounted on said member adjacent the periphery thereof, said magnet having a wedge shaped outer portion with the apex arranged transversely of the member, a stationary magnetic pick-up head mounted adjacent the periphery of said member, means for rotating said member in synchronism with said shear drum so that said magnet passes said pick-up head at the same time as the shear is cutting, and a magnetic shield surrounding said pick-up head, said shield having an opening therein on the side facing the member, said opening flaring outwardly away from said member.

3. In combination with a rotatable shear drum a magnetic impulse generator comprising a rotatable non-magnetic member, a single magnet mounted on said member adjacent the periphery thereof, said magnet having a wedge shaped outer portion with the apex arranged transversely of the member, a stationary magnetic pick-up head mounted adjacent the periphery of said member, said pick-up head having a core and a coil surrounding said co're, means for rotating said member in synchronism with said shear drum so that said magnet passes said pick-up head at the same time as the shear is cutting, and a magnetic shield surrounding said pick-up head, said shield having an opening therein on the side facing the member, said opening flaring outwardly away from said member.

4. In combination with a rotatable shear drum, a magnetic impulse generator comprising a rotatable shaft, a non-magnetic ring mounted on said shaft for rotation therewith, a single magnet mounted on said ring adjacent the periphery thereof, a stationary magnetic pick-up head mounted adjacent the periphery of said ring, means for rotating said shaft in synchronism with said shear drum, means for adjustably positioning said magnet angularly with respect to said shear drum and said pick-up head so that said magnet passes said pick-up head at the same time as the shear is cutting, and a magnetic shield surrounding said pick-up head, said shield having an opening therein on the side facing the ring, said opening being the lines of fiux around the pick-up head until said magnet is approximately in alignment with said opening.

5. A magnetic impulse generator comprising a rotatable shaft, a non-magnetic ring mounted on said shaft for rotation therewith, a single magnet mounted on said ring adjacent the periphery thereof, a stationary magnetic pickup head mounted adjacent the periphery of said ring, means for rotating said shaft, and a magnetic shield surrounding said pick-up head, said shield having an opening therein on the side facing the ring, said opening flaring outwardly away from said ring.

References Cited in the file of this patent UNITED STATES PATENTS Fiske Oct. 5, 1897 Severy et a1. Apr. 27, .1915 Heath Feb. 27, 1934 Guenther Feb. 11, 1941 Potter Ian. 13, 1942 Fritzinger July 19, 1949 Elam June 12, 1951 Sias Dec. 18, 1951 Ainsworth Feb. 17, 1953 Cathcart -4-.. July 27, 1954 

